One year after: outcome and finishing

Deformation of bodies

The deformation is back, but moderately. In any case, the bodies hold easily on their chassis.

Space between bellows

As envisaged, the buffer bushels have been bored about 0.5 mm, first with a ø 2 mm carbide drill bit, then, as it was a little too narrow, with a small ø 2.2 mm milling bit visible at the bottom of the photo. Of course, this would have been simpler with a ø 2.2 mm drill bit. This is done with a hand drill holder.

Boring the buffer bushels

Correction of height

I now deal with the glaring difference in height between the motor car and the trailer. The motor car is too low: it lacks about 1 mm in absolute. But I will just adjust its height to the trailer’s, that is an increase of about 0.8 mm.

Difference of height between motor car and trailer

This correction makes me a little afraid because the bogies are mounted on a ball joint support cast with the chassis. No correction possible with plastic spacers for example. It is necessary to act on the support itself, gently but firmly, so as not to risk the breakage.

Here again, I regret that Roco did not treat the motor car with a single motor bogie, as in reality. The rear bogie would then have been trailing and would not have posed so many difficulties. But finally, the bogie is disassembled easily enough: do not be afraid to force a little to disengage the ball joint No. 2 (the piece No. 1 which locks it in its housing is a small plastic fork soft enough).

Rear motor bogie removed

Note that the rear gimbal will fall off when dismantling. Its repositioning will be much simpler by removing the worm gear from its housing, removing its bonnet held by four small clips.

I tinker a kind of extractor with two pieces of asymmetrical DIN rail, well known to electrotechnicians. It is really an infamous tinkering, not even symmetrical (and for a good reason!), But I do not want to make an impeccable tool for a single use. I imagine there should be mini-extractors for sale that might be suitable.

At the rear, the initial height measured with a caliper between the top of the chassis and the ball joint is 12.5 mm. I should theoretically bring it to 12.5 + 0.8 = 13.3 mm. But I save you the many tests: it turns out that it is better to push to 13.5 mm. At the front, 0.8 mm will be enough.

Lifting by deformation of the ball joint support

  1. Ball joint of the bogie support
  2. Extractor claw
  3. Extractor M6 screw; its 1 mm pitch makes it possible to easily estimate the displacement of the ball joint.

Let’s not forget to add about 0.75 mm thick Evergreen spacers under the bosses of the 2-point suspension.

2-point suspension spacers at the front

If you want a less ugly and yet inexpensive tool, here is what I propose. The part comes from a rectangular steel tube found in a DIY superstore at €8.30 per metre. The screw has its end turned in a truncated cone and possibly hollowed out to better centre itself on the ball joint. One can also more simply use an M5 or M4 screw.

Improved extractor

Deforming the support up to 1 mm was a bit risky, but it went well, and this gives a very correct result, as shown in this photo. A very small gap remains between the bellows, but it is now constant. I could have made a drawbar a bit shorter (I recall that for the NEM standard, the space between the coupling boxes must be 15 mm, which I have already reduced to 14).

RGP coupling with corrected height

OK! The buffers are now a little too far apart… And I have to put the brake rod back.